The instant invention relates to the stabilization of a wide variety of ambient cured coating compositions by the incorporation therein of N-hydroxy-substituted hindered amine light stabilizers.
Hindered amine light stabilizers are well known to be effective in stabilizing a host of organic substrates including polymers against the deleterious effects of oxygen and light. Such hindered amine light stabilizers have been used in the stabilization of hot-crosslinkable alkyd or acrylic metallic stoving lacquers (U.S. Pat. No. 4,426,472) and in stabilizing acid-catalyzed stoving lacquers based on hot-crosslinkable acrylic polyester or alkyd resins (U.S. Pat. Nos. 4,344,876 and 4,426,471). The hindered amine light stabilizers of these patents do not possess structures having a hydroxyl group substituted directly on the hindered N-atom of the compound.
Related hindered amine stabilizers have been utilized individually and in combination with ultra-violet light absorbers to improve the performance characteristics of ambient cured coating systems. Notwithstanding such improvements, there still exists a need to further retard the photooxidation and photodegradation of such ambient cured systems and thereby provide increased effectiveness by maintaining the physical integrity of the coatings. Such effectiveness can be manifested by prevention of embrittlement, cracking, corrosion, erosion, loss of gloss, chalking and yellowing of the coating.